In wiper blades, the support element is meant, over the entire wiping field swept by the wiper blade, to assure that most uniform possible distribution of the wiper blade contact pressure against the window or glass, which pressure originates in the wiper arm. By elementxe2x80x94that is, when the wiper blade is not resting against the windowxe2x80x94the ends of the wiper strip, placed entirely against the window during operation of the wiper blade, are urged toward the window by the then-tensed support element, even if the radii of curvature of spherically curved vehicle windows change at each wiper blade position. The curvature of the wiper blade must accordingly be somewhat greater than the maximum curvature measured in the wiping field of the window to be wiped. The support element thus replaces the complicated support bracket construction with two spring rails disposed in the wiper strip of the kind used in conventional wiper blades (German Published, nonexamined Patent Application DE-OS 15 05 357).
The invention is based on a wiper blade as generically defined by the preamble to claim 1. In a known wiper blade of this type (U.S. Pat. No. 3,785,002), a shield-like termination part is disposed on each of its two end portions; with a comparatively long tongue, it rests on the top side, remote from the window, of the support element that is constructed of two leaf springs one above the other, and for securing the mounting position in the longitudinal direction, it has a cam that engages a recess of the upper leaf spring. Crosswise to the length of the wiper blade, the position securing is effected by means of a tunnel-like embodiment of the wiper strip on its two end regions that surround the support element together with the tongues of the two termination parts. The thus-fixed termination parts completely cover the ends of the wiper strip in the region of the sharp-edged support element. The design of the known wiper blade requires cost-intensive production processes both for the wiper strip and for the support element and the termination parts. Mounting the known wiper blade furthermore requires a plurality of mounting steps that can be done only by hand. Finally, the tongues of the termination parts stiffen the ends of the support element, whichxe2x80x94especially in the case of spherically curved windowsxe2x80x94has an unfavorable effect on the desired uniform distribution of contact pressure of the wiper strip against the window.
In the wiper blade according to the invention, the termination part can be embodied as short enough that no impairment of the elasticity of the support element occurs. The wiper strip can have a constant cross section over its entire length, and thus it can be produced economically by extrusion. Mounting the two termination parts is also done in a simple way by snapping them onto the support element or onto the already preassembled wiper blade, with the wiper strip retained on the support element. This snapping action can also be done by means of an automatic mounting station. The termination parts thus snapped on prevent injuries to persons handling the wiper blade from the ends of the support element, which as a rule have sharp edges.
If the support element is embodied as a one-piece spring band, on one band face of which, toward the window, the wiper strip is secured, and from the other band face of which, remote from the window, the detent shoulder protrudes, the support element can be produced economically and without waste from spring band steel.
In a detent shoulder embodied in this way, it is expedient if on the side of the termination part base body toward the support element, a throat is disposed, on which the counterpart shoulder of the termination part is embodied.
In certain advantageous production methods for the support element, it can happen that some protrusions remain on the long sides of the end regions of the support element, and these protrusions make it more difficult for the termination parts to snap cleanly onto the support element. These restrictions are avoided if cavities for receiving protrusions protruding from the long sides of the support element are disposed in the hook legs, crossing the support element, of the hook-like extensions of the termination part.
In certain versions of the wiper blade, it can be advantageous if the support element is embodied as a one-piece spring band, on one band face of which, toward the window, the wiper strip is secured, and the detent shoulder is embodied on at least one of the two long sides of the support element. It is possible in this respect to provide the detent shoulder on a peripherally open, partial recess disposed laterally on the support element.
An inexpensive embodiment of the counterpart shoulder is attained if the counterpart shoulder is embodied on the hook legs of the hook-like extensions of the termination part that cross the support element.
Especially whenever the width of the support element narrows toward its two ends, it is advantageous if the detent shoulder is embodied on a detent tooth that protrudes from the long side of the support element.
In another production process for the support element, which is expedient in certain cases, it can happen that some small protrusions remain on the face ends of the support element that prevent the termination parts from being snapped onto the support element. If such a method is employed, it has proved advantageous if a recess for receiving a protrusion protruding from the face end of the support element is disposed on the inside wall, covering the face end of the support element, of the termination part.
A further embodiment of the wiper blade of the invention is distinguished in that the hook-like extensions that cross the support element and engage the side of the support element toward the window from behind are each joined by a respective film hinge to the base body of the termination part. The result is an especially simple mounting of the termination parts on the support element, because they merely have to be placed in their operating position on the support element, or on the support element already equipped with the wiper strip; after that, the hook-like extensions need merely be hinged into their securing positions.
Additional security of the connection between the support element and the wiper strip is obtained if the wiper strip, on both of its long sides, has a respective longitudinal groove, the inside of which is engaged by the claw legs, oriented toward one another and disposed on the hook legs, of the termination part.
In a further embodiment of the wiper blade, which is expedient for certain applications, the support element has two elongated, spring-elastic retaining rails, which are each disposed one of the two longitudinal grooves extending along both long sides of the wiper strip, and the retaining rails protrude with their long edges remote from one another out of their longitudinal grooves of the wiper strip, and the detent shoulder is embodied on at least one of these two long edges.
In a wiper blade constructed in this way, the counterpart shoulder of the termination part that is associated with the detent shoulder of the retaining rails are disposed on the hook-like extensions that cross the support element having the two retaining rails. Besides the simple mounting of the termination parts, the result, at no additional effort or expense, is that the two retaining rails are reliably secured in their mounting positions of the wiper strip.
The desired simplicity of fastening the termination parts to the support element or wiper blade can be achieved especially well, along with economical production, if the termination part is made from an elastic plastic.